The brain-pituitary-adipocyte axis: role of leptin in modulating neuroendocrine function.

The recently discovered protein leptin has a molecular mass of 16 kDa, consists of 146 amino acids, and is synthesized and secreted by adipose tissue. Leptin affects feed intake, the neuroendocrine-axis, and immunological processes. The protein was first identified as the gene product that is deficient in the obese ob/ob mouse. Leptin serves as a circulating signal of nutritional status and plays a pivotal role in regulation of body weight, energy expenditure, growth, and reproduction.